Door knob



FIG. 1 is a perspective view of a door knob showing my new design;

FIG. 2 is an enlarged front elevational view thereof, the rear being unornamented;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a top plan view thereof, the bottom being a mirror image; and,

FIG. 5 is a top plan view thereof in an alternate position. 

The ornamental design for a door knob, as shown and described. 